London Advancing Bitcoin Tutorial

Content for Following Along!

Other people have followed this tutorial with some success:

https://gnusha.org/ctv-bip-review/2022-02-22.log

If you’re having a problem, see above log where people have had issues. Common problems include:

1. Not building latest sapio binary
2. Not having the correct clang version (>=12)
3. brew installing clang somewhere else (try /opt/homebrew, but also /usr/local/Cellar)
4. xargs not liking something (working to debug it, you can open the JSONs with vi and do by hand some of the steps).

1. Install JQ (json manipulating tool) if you don’t have it / other things needed to run a bitcoin node.
2. Set up a signet node.

Build this branch https://github.com/JeremyRubin/bitcoin/tree/checktemplateverify-signet-23.0-alpha

You’ll likely want settings like this in your bitcoin.conf too:

[signet]
# generate this yourself                                                                                                                    rpcauth=generateme:fromtherpcauth.pyfile     
txindex=1
signetchallenge=512102946e8ba8eca597194e7ed90377d9bbebc5d17a9609ab3e35e706612ee882759351ae 
rpcport=18332
rpcworkqueue=1000
fallbackfee=0.0002

Get coins https://faucet.ctvsignet.com/ / DM me

1. Follow the install instructions on https://learn.sapio-lang.org/ch01-01-installation.html You can skip the the sapio-studio part / pod part and just do the Local Quickstart up until “Instantiate a contract from the plugin”. You’ll also want to run cargo build –release from the root directory to build the sapio-cli.

2. Open up the site https://rjsf-team.github.io/react-jsonschema-form/
3. Run sapio-cli contract api –file plugin-example/target/wasm32-unknown-unknown/debug/sapio_wasm_plugin_example.wasm
4. Copy the resulting JSON into the RJSF site
5. Fill out the form as you wish. You should see a JSON like

   {
     "context": {
    "amount": 3,
    "network": "Signet",
    "effects": {
      "effects": {}
    }
     },
     "arguments": {
    "TreePay": {
      "fee_sats_per_tx": 1000,
      "participants": [
        {
          "address": "tb1pwqchwp3zur2ewuqsvg0mcl34pmcyxzqn9x8vn0p5a4hzckmujqpqp2dlma",
          "amount": 1
        },
        {
          "address": "tb1pwqchwp3zur2ewuqsvg0mcl34pmcyxzqn9x8vn0p5a4hzckmujqpqp2dlma",
          "amount": 1
        }
      ],
      "radix": 2
    }
     }
   }
   

   You may have to delete some extra fields (that site is a little buggy).

Optionally, just modify the JSON above directly.

1. Copy the JSON and paste it into a file ARGS.json
2. Find your sapio-cli config file (mine is at ~/.config/sapio-cli/config.json). Modify it to look like (enter your rpcauth credentials):

   {
     "main": null,
     "testnet": null,
     "signet": {
    "active": true,
    "api_node": {
      "url": "http://0.0.0.0:18332",
      "auth": {
        "UserPass": [
          "YOUR RPC NAME",
          "YOUR PASSWORD HERE"
        ]
      }
    },
    "emulator_nodes": {
      "enabled": false,
      "emulators": [],
      "threshold": 1
    },
    "plugin_map": {}
     },
     "regtest": null
   }
   

3. Create a contract template:

   cat ARGS.json| ./target/release/sapio-cli contract create  --file plugin-example/target/wasm32-unknown-unknown/debug/sapio_wasm_plugin_example.wasm  | jq > UNBOUND.json
   

4. Get a proposed funding & binding of the template to that utxo:

cat UNBOUND.json| ./target/release/sapio-cli contract bind | jq > BOUND.json

1. Finalize the funding tx:

cat BOUND.json | jq ".program[\"funding\"].txs[0].linked_psbt.psbt" | xargs echo | xargs -I% ./bitcoin-cli -signet utxoupdatepsbt % |  xargs -I% ./bitcoin-cli -signet walletprocesspsbt % | jq ".psbt" | xargs -I% ./bitcoin-cli -signet finalizepsbt % | jq ".hex"

1. Review the hex transaction/make sure you want this contract… and then send to network:

   ./bitcoin-cli -signet sendrawtransaction 020000000001015e69106b2eb00d668d945101ed3c0102cf35aba738ee6520fc2603bd60a872ea0000000000feffffff02e8c5eb0b000000002200203d00d88fd664cbfaf8a1296d3f717625595d2980976bbf4feeb
   10ab090180ccdcb3faefd020000002251208f7e5e50ce7f65debe036a90641a7e4d719d65d621426fd6589e5ec1c5969e200140a348a8711cb389bdb3cc0b1050961e588bb42cb5eb429dd0a415b7b9c712748fa4d5d
   fe2bb9c4dc48b31a7e3d1a66d9104bbb5936698f8ef8a92ac27a650663500000000
   

2. Send the other transactions:

cat BOUND.json| jq .program | jq ".[].txs[0].linked_psbt.psbt" | xargs -I% ./target/release/sapio-cli psbt finalize --psbt %  | xargs -I% ./bitcoin-cli -signet sendrawtransaction %

Now what?

• Maybe load up the Sapio Studio and try it through the GUI?
• Modify the congestion control tree code and recompile it?
• How big of a tree can you make (I did about 6000 last night)?
• Try out other contracts?